The present invention relates to a breathable garment to be worn in order to improve the comfort of the human body.
It is known that people protect their body from atmospheric agents such as snow, rain, wind and particularly from the cold by wearing garments and footwear.
More specifically, it is noted that the human body is protected mainly by resorting to various "layers" of clothing, the first of which (underwear) is in direct contact with the body and is in turn covered by successive layers according to the outside temperature and to the environmental conditions.
Use of this kind of protection from the outside allows the body to easily adapt to temperature variations.
Depending on the environmental conditions in which a person find himself, it is in fact sufficient to add or remove one or more "layers" of clothing to feel comfortable and be at an optimum temperature.
For example, in the presence of rain it is commonplace to use a raincoat to protect oneself or to remove one's coat when arriving from outdoors into a heated environment.
The human body is inherently provided with "mechanisms" which help it adapt thermally in the environment in which it is placed.
In case of overheating, for example, the body reacts by increasing perspiration, which by evaporating allows a natural reduction of body temperature.
The heat produced by the human body, in addition to generating perspiration, is also transferred to the outside environment by radiation.
This heat, which is always present, warms the air contained between the body and the garment; said air, by rising, produces further overheating and discomfort, for example at the shoulders, which constitute regions of accumulation.
In order to obviate this drawback, it is necessary to produce or maximize a ventilation effect (air change) inside the garment regardless of the release of vapor, utilizing the differences in pressure that occur between the inside and the outside of the garment.
For example, with an outside temperature of 5.degree. C. and a relative humidity of 50% and with the body at 25.degree. C. and a relative humidity of 90%, the resulting pressure differential is approximately 24 millibar and is not a negligible factor.
If the water vapor is unable to escape from the protective covering that surrounds the human body (clothing), the humidity increases until the vapor condenses and returns to the liquid state of perspiration, thus soaking the clothes starting from the underwear that constitutes the first layer.
During this step of the process there is actually a further release of heat.
This unpleasant drawback can be remedied by removing the wet garment and replacing it with a dry one, for example immediately after completing a challenging mountain climb, but in this way one produces a sudden cooling of the body and risks pneumonia or colds.
While on the one hand the protection of the human body against the worst cold conditions is very effective, by using highly insulating materials, on the other hand one cannot avoid noting the inability to allow the body to perspire normally, ensuring the escape of the water vapor produced by perspiration.
Obviously, during the warm season the problem becomes more intense and forces many people to take several showers and continuously change clothing during the day.
Attempts have been made to remedy this drawback by using garments provided with special breathable properties, for example by resorting to a material known commercially by the trademark "Gore-Tex", owned by the company W.L. Gore & Associates, Inc.; however, in practice such garments are able to expel only part, often a very small part, of the vapor produced by perspiration and generated by the human body, especially at the regions that are richest in sweat glands, and in any case they are unable to ensure effective air change inside the garment.
Vapor permeation in fact occurs to a reduced extent, since inside the layer of the garment being worn the partial vapor pressure that forms is not sufficient to expel the sweat (in the vapor phase) outward.
In other cases, remedies have been attempted by providing more or less closeable openings in the garments at the regions where perspiration concentrates more, for example under the armpits, but even this does not ensure particular effects, since no actual air change is produced.
It should also be noted that even the attempt to increase effectiveness by providing a larger number of openings has failed to yield satisfactory results.
In practice, in fact, some parts of the garments always cling directly to the human body (particularly to the shoulders and chest), so that the water vapor generated by evaporation of body sweat remains trapped between the body and the regions of the garments that do not cling directly to the body (generally the abdomen, the lumbar region of the back, and particularly the region under the armpits), thus preventing its escape.
In other known cases, for example in U.S. Pat. No. 4,451,934 for a garment to be used under a non-porous outergarment, such as personal body armor for military personnel, workers exposed to high temperatures, firemen, which does not convey the water vapor to the environment, channels have been provided inside the garment, which prevents the contact of the outergarment with the wearer and in which the air and vapor can circulate and are conveyed upward by convection and then conveyed into the atmosphere.
The channels are open inward and at the ends in order to be able to receive the vapor produced by perspiration by the body and expel it, but in any case they do not prevent the penetration of liquids (water or other dangerous chemicals) from the outside toward the inside through the open ends, exposing the wearer of the garment to significant risks and discomfort.
In any case, this is still an undergarment which must always be used in combination with an outergarment, for which it reduces the problems arising from its non-porous nature.